<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="../css/bootstrap.css">
    <title>Bootstrap图片</title>
</head>
<body style="background-color: gray;">
    <!-- 给图片添加圆角边框 -->
    <img src="../images/img.png" class="rounded"  alt="">
    <!-- 给图片添加圆形边框 -->
    <img src="../images/img.png" class="rounded-circle" alt="">
    <!-- 给图片添加相框，并具有可伸缩的效果 -->
    <img src="../images/img.png" class="img-thumbnail" alt="">
    <!-- 响应式图片 -->
    <img src="../images/img.png" class="img-fluid" height="1200px" width="1600px" alt="">
    <hr>
    <!-- embed-responsive-21by9 可以用于控制iframe的长宽比 -->
    <div class="embed-responsive embed-responsive-21by9">
        <iframe class="embed-responsive" src="https://www.baidu.com/" ></iframe>
    </div>
    <hr>
    <!-- 图片的对齐 -->
    <img src="../images/img.png" class="float-left"   height="200px" width="200px" alt="">
    <img src="../images/img.png" class="float-right" height="200px" width="200px" alt="">
    
</body>
</html>